As shown in FIG. 11, a multi-layered optical recording medium 31 with a two-layer construction is known as a multi-layered optical recording medium of this type. The multi-layered optical recording medium 31 is a so-called “single-sided” multi-layered optical recording medium, where a cover layer C as a first resin layer, a recording layer L0 as a first recording layer, a spacer layer SP as a second resin layer, and a recording layer L1 as a second recording layer L1 are formed, in descending order of distance to a plate-like (for example, a disc-shaped) base D, on the base D that has a fitting center hole H formed in a center part thereof. In this case, the base D is manufactured using a resin material, such as polycarbonate, and fine minute convexes and concaves (not shown), such as grooves (guide grooves) and lands, are formed on a surface (the upper surface in FIG. 11) on the cover layer C side of the base D. The recording layer L1 as the second recording layer is composed of laminated layers such as a reflective film that is provided on these grooves, lands, etc., and reflects a laser beam set at a recording power and a laser beam set at a reproduction power (both are which are hereinafter referred to as the “laser beam” when distinction is not required), a phase change film whose reflectivity changes with changes in the optical constant due to irradiation with a laser beam set at the recording power, and a protective film that protects the phase change film. In this case, as one example, the reflective film, the phase change film, and the protective film are formed as thin films by sputtering non-organic materials such as metal materials and inorganic materials.
The spacer layer SP as the second resin layer is formed of light transmitting resin and has fine minute convexes and concaves (not shown) of grooves, lands, etc., formed in a surface of a cover layer C side thereof. The recording layer L0 as the first recording layer is composed of laminated layers such as a phase change film, protective film, and the like formed on these grooves, lands, etc. In this case, in the same way as the recording layer L1, the phase change film and protective film of the recording layer L0 are formed as thin films by sputtering non-organic materials, for example. The cover layer C as the first resin layer is formed of a light transmitting resin.
In this case, as shown in FIG. 11, the recording layers L0, L1 are formed so that the respective entire inner circumferential edges thereof are positioned a distance E (more specifically, around 1 mm) towards an outer periphery from inner circumferential edges of the spacer layer SP and the cover layer C, and the respective entire outer circumferential edges thereof are positioned a distance F (more specifically, around 1 mm) towards an inner circumference from an outer circumferential edges of the spacer layer SP and the cover layer C.
By irradiating the multi-layered optical recording medium 31 with a laser beam generated by an optical pickup in the direction shown by the arrow A in FIG. 11 (i.e., from the side of the base D on which the recording layers L1, L0, and the like are laminated), the recording of recording data onto the recording layers L0, L1 and the reproduction of recording data from the recording layers L0, L1 are carried out.